1. Field of the Invention
The present invention relates to methods and apparatus for mixing an additive with a compound having a viscous and stiff consistency, and more particularly to methods using a hand held manually operated mixer capable of distributing an additive throughout such a compound disposed inside a retail dispensing tube.
2. Description of the Prior Art
Compounds used for caulking and grouting are formulated to be workable but viscous and relatively stiff. These compounds are formulated for application to joints and cracks by pressing the compound into an opening and smoothing the exposed surface, with the use of a tool designed for the purpose. The stiffness prevents the material from readily migrating, after application, even when the compound is applied on a vertical wall. The viscosity causes the compound to adhere to the surfaces in cracks and joints to achieve a complete filling of the space, even when the compound is dragged somewhat by the smoothing phase of the work.
Unfortunately, the viscosity and stiffness, which make the compounds suitable for grouting and caulking also make the compounds difficult to handle. Suppliers have responded by delivering compounds for caulking and grouting in retail dispenser tubes. The tubes are typically a plastic or lined paperboard cylinder with a fixed wall at a front end and a thrust cap at an opposite filler end. The fixed wall is provided with a centered hole, through which a tapered dispenser tip extends. The supplier fills the tube, through the filler end and inserts the thrust cap to seal the compound inside the cylinder. The user opens the tube, for use, by cutting the dispenser tip at a location selected to provide an opening of desired diameter. The user places the tube in a caulking gun, which is configured with a ratchet driven trigger mechanism for gradually advancing a push rod. The push rod engages the thrust cap, of the tube, and presses the thrust cap forward through the tube to dispense the compound through the opening in the tip. The user may move the tip over an area where the compound is to be applied while operating the trigger mechanism to dispense the compound at a desired rate. The compound may be smoothed after it is applied to finish the job. The retail tube and calking gun allow a user to dispense the compound directly where it is needed without the necessity of removing the compound from the tube or otherwise handling the compound prior to use.
The retail tube and caulking gun are ideal for pre-mixed or one step compounds, which can be sold in the ready-to-use tubes; however, when an additive is required, the user must handle the compound to some extent. Certain quick setting compounds require that a catalyst be added immediately before use. For certain caulking jobs, it is desirable that the caulking compound be tinted with colorant before use, in order to match the compound with the color of adjacent surfaces such as walls or ceilings. While it is possible to add colorant in advance, it is not practical for a supplier to provide various compositions of caulking compound in all color variations. It is standard practice to purchase an untinted caulking compound and to add the colorant by mixing. When a fast acting catalyst is required or when color tinted caulk is needed, the user must mix an additive with the compound.
In order to minimize the handling of the compound, typical conventional methods of mixing an additive with caulking or grouting compound are practiced with the compound remaining in the retail tube. A U.S. Patent Application 2006/0151531, to Tikusis discloses a method of supplying the additive in a separate reservoir, which is disposed in the tube beside the compound. The additive and the compound are dispensed simultaneously into the dispenser tip and are mixed as they are dispensed. Another method, disclosed by U.S. Pat. No. 4,114,196, to Lostutter, uses a frame configured to hold retail tubes of compound and adapted for loading on a conventional paint shaker. The thrust cap is removed, the additive introduced to the compound inside the tube, and the tube is shaken to mix the additive and the compound. Finally, U.S. Pat. No. 7,070,318, to Renfro discloses a mixer blade mounted on a shaft. A mixer head is slidably and rotatably mounted on the shaft and the mixer head is configured for sealable engagement with the filler end of the tube. Two motors are used to rotate and reciprocate the mixer blade inside the tube containing the additive and the compound.
Alternatively, one motor may be used to rotate the mixer blade and reciprocation may be supplied manually in the manner of a soda fountain milkshake mixer. The mixer blade is designed with a continuous circumferential edge which is intended to remain adjacent to the inside surface of the tube, for scraping the compound from the side of the tube during the mixing operation.
Generally, the method of mixing the additive and the compound in the dispensing tip, at the point of application does not yield acceptable results, particularly in the case of color tinting, where a thorough and even dispersal of the colorant is necessary to achieve uniform appearance. The mechanical shaker of Lostutter and the mixing apparatus of Renfro require bulky equipment and a power source. These methods are suitable for mixing, by the retailer, at the point of sale.
There is a need for an effective apparatus and method of mixing an additive into a compound, in the retail tube, which can be used at a work site.
There is a need for an effective apparatus and method of mixing an additive into a compound, in the retail tube, which does not require bulky equipment or a power source.
Finally, there is a need for a hand held manually operated mixer and method for mixing an additive into a compound, in the retail tube.